<html><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><br><div><div>On Apr 10, 2009, at 11:22 PM, <<a href="mailto:grass-user-request@lists.osgeo.org">grass-user-request@lists.osgeo.org</a>> wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span style="font-family: Helvetica; font-size: medium; color: rgba(0, 0, 0, 0.496094); "><b>From:<span class="Apple-converted-space"> </span></b></span><span style="font-family: Helvetica; font-size: medium; ">Markus Neteler <<a href="mailto:neteler@osgeo.org">neteler@osgeo.org</a>><br></span></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span style="font-family: Helvetica; font-size: medium; color: rgba(0, 0, 0, 0.496094); "><b>Date:<span class="Apple-converted-space"> </span></b></span><span style="font-family: Helvetica; font-size: medium; ">April 10, 2009 11:12:40 PM GMT-07:00<br></span></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span style="font-family: Helvetica; font-size: medium; color: rgba(0, 0, 0, 0.496094); "><b>To:<span class="Apple-converted-space"> </span></b></span><span style="font-family: Helvetica; font-size: medium; ">Tripp Lowe <<a href="mailto:tripplowe@gmail.com">tripplowe@gmail.com</a>><br></span></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span style="font-family: Helvetica; font-size: medium; color: rgba(0, 0, 0, 0.496094); "><b>Cc:<span class="Apple-converted-space"> </span></b></span><span style="font-family: Helvetica; font-size: medium; ">GRASS user list <<a href="mailto:grass-user@lists.osgeo.org">grass-user@lists.osgeo.org</a>><br></span></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span style="font-family: Helvetica; font-size: medium; color: rgba(0, 0, 0, 0.496094); "><b>Subject:<span class="Apple-converted-space"> </span></b></span><span style="font-family: Helvetica; font-size: medium; "><b>Re: [GRASS-user] NED Shaded Relief, Grass 6.4</b><br></span></div><br><br>Tripp,<br><br>On Sat, Apr 11, 2009 at 8:05 AM, Tripp Lowe <<a href="mailto:tripplowe@gmail.com">tripplowe@gmail.com</a>> wrote:<br><blockquote type="cite">Hello Folks,<br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite">I am trying to create a shaded relief map based on a 30-meter NED file using<br></blockquote><blockquote type="cite">r.shaded.relief. The results are very 'blocky' (or stair-stepped). Running<br></blockquote><blockquote type="cite">a 5-cell average neighborhood across the DEM did not help. Can somebody tell<br></blockquote><blockquote type="cite">me the correct procedures I should follow to create the relief map that is<br></blockquote><blockquote type="cite">smooth?<br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite">I've put a screenshot of my initial shaded relief map up here to show you<br></blockquote><blockquote type="cite">what I'm talking about...<br></blockquote><blockquote type="cite"><a href="http://www.rlogis.com/GMaps/test/grass64_shadrel.jpg">http://www.rlogis.com/GMaps/test/grass64_shadrel.jpg</a><br></blockquote><br>did you run<br>g.region rast=your_ned_map -p<br><br>before<br>r.shaded.relief<br>? I suspect that your current region is of lower resolution right now.<br><br>Markus<br><br><br></span></blockquote><br></div><div>Additionally, NED data are not very good in this respect. In many (all?) cases, they are DEM's interpolated from contour maps, which were hand or machine drawn from aerial photo data with surveyed reference points. They tend to have inherent stair steps. So even if you get rid of the blocks, it still probably won't be the kind of shaded relief that you want. For North America, the 30m SRTM level 3 or 4 data are much better.</div><div><br></div><div>Michael</div><br></body></html>